Techniques for measuring a temperature of plasticized resin in an injection mechanism by use of a thermocouple have been known from, for example, Japanese Patent Laid-Open Publication No. HEI-6-246786.
FIG. 9 hereof is a sectional view explanatory of the plasticized resin temperature measuring technique disclosed in the HEI-6-246786 publication, wherein reference numeral 1 represents a heating cylinder, 2 a nozzle, 4 a thermocouple and 4b a piano wire. The disclosed technique is intended to measure a temperature of resin 5, and particularly plasticized resin, using the thermocouple 4. The thermocouple 4, exposed to a flow of resin, tends to be undesirably displaced from a predetermined position, and thus the piano wire 4b or other suitable thermocouple retaining member is essential to prevent the displacement of the thermocouple 4. Further, the nozzle 2 must be indispensably accompanied by the thermocouple 4, which would add to manufacturing costs. Namely, with the disclosed conventional technique, the provision of the thermocouple 4 in the nozzle 2 not only increases the necessary manufacturing costs but also complicates the overall structure of the nozzle 2. Because of the complicated structure of the nozzle 2, the nozzle 2 etc. have to be handled with due care, which would result in lowered productivity.